Aurora Polaris

Aurora polaris, known in the Northern hemisphere as aurora borealis (northern lights) and in the Southern hemisphere as aurora australis (southern lights), is caused by electrons of the solar wind (typical energy 1-15 keV) colliding with oxygen, nitrogen and other gasses in the upper atmosphere.

Oxygen produces the most prominent auroral light, emitting green light at wavelength 557.7 nm and red at 630.0 nm. Other spectral lines in Earthly auroras result from collisions with nitrogen and other atmospheric gasses, though these are less visible than the photon emissions of oxygen.

Below, the aurora is viewed from aboard the ISS, at an altitude of approximately 350km:

Here’s a brief time-lapse video of aurora over British Columbia, Canada:

Duration 0:01:04